Telephone system



A. E. LUNDELL. TELEPHONE SYSTEM.

APPLICATION FILED JULY 27,1916.

Patented Dec. 28,1920.

3 SHEETS-SHEEI l Alba/'7 E. Luna/ell.

Aff'y.

A. E. LUNDE'LL.

TELEPHONE SYSTEM.

APPUCATION FIL'ED JULY 27.1916.

Patented- Dec. 28, 1920.

3 SHEETS-SHEET 2.

lnvenfor: A/ben E. Luna/ell.

/i Hy,

A. E. LUNDELL.

TELEFHQNE SYSTEM.

APPLICATION FILED JULY 27,1916.

Patented Dec. 28,1920.

3 SHEETS SHEET 3.

LMR

A/ben E. Lunafe/l.

Affy.

Uhll'i STATE ALBEN E. IPANY,

o PATENT CFFICE.

LUNDELL, OE NEW YORK, N". Y., ASSIGNOR TO WESTERN ELECTRIC COM- INCORPORATED, 015 NEW!" YGRK,

N. Y., A CORPORATION OF NEW YORK.

TELEIPHCNE SYSTEM.

Application filed July 27,

To all whom it may concern:

Be it known that I, ALBEN E. LUNniLL, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to that particular type or class of telephone systems wherein automatic switches are employed in establishing more or less or" the talking circuits between subscribers lines under the control of a sending mechanism, and which may be modified by the depression of keys to establish a condition corresponding to the numher of the line of the desired subscriber.

The invention comprises a certain novel circuit arrangement particularly associated with the sending mechanism, in which a rotary wiper switch is employed instead of relays, as heretofore, to determine the number of impulses transmitted to the automatic switches employed in establishing talking connections. The present invention is, in a certain sense, an improvement on the circuit arrangements of my prior U. S. Patent No. 1,168,319, granted Jan. 18, 1916, wherein relays were employed for this purpose.

The various features of the invention will be more fully understood upon reference to the following detail description taken in connection with the accompanying drawing, and the scope of the invention will be pointed out in the appended claims.

In the drawing, Figures 1, 2 and 3 when arranged in the manner indicated by Fig. 4 form a circuit diagram of a system with which my invention is adapted to be used.

In the system diagrammatically illus trated in these figures, a calling subscribers line is manually connected to a cord circuit and the circuit of the latter is extended through automatic switches to the calledtor line in response to impulses transmitted from the sending mechanism located before an operator. Obviously, the invention is capable of application to systems requiring other connections, but the system of the present diagram constitutes a typical embodiment of the invention.

The calling subscribers line extends from a sub-station M having the usual equipment to a central ofhce, where it terminates in Specification of Letters Patent.

Patented Dec. 28, 1920.

1916. Serial N0. 111,586.

contacts or" a jack J and is extended through normal contacts of a cut-off relay CO, and the winding of a relay LE to the opposite poles of the battery. The latter relay has associated wlth it the usual line lamp L. The called line L extends from a similar sub-stat on N to the terminal of a switch S The link circuit L is connected to the line L by insert ng a plug P into the jack J, and its circuit is extended toward the called-for l ne through a first selector switch S, a link c rcuit L a second selector switch S a link circuit L and a connector switch S The heavy lines indicate the talking circuit established between the sub-stations hi and N.

Any desired number of switches may be employed in establishing a connection, but for the purposes of the present illustration, three such switches are indicated, the switch S in detail, and the switches. S and S merely having their contacts shown.

In establishing connection between the sendlng mechanism of Figs. 2 and 3, a cord finder switch S is employed. This is similar in construction to the switch S.

Both of these switches are of the vertically movable type, and wipers are moved up and down in response to the driving action of constantly rotating disks brought into play n one instance by an advancing magnet, and in the other instance by a return magnet. This type of switch is fully disclosed in U. S. Patent to Reynolds, No. 1,103,628, dated July 14, 1914.

The rotary switch, which is brought into play in determining the impulses that should be transmitted to bring about the properoperation of the switches S, S and S is shown in Fig. 2, where it is designated S. This switch is of the rotary type and is advanced step by step by the actuations of a motor magnet MM controlled by stepping relay ST, and returned to normal position by a further advance brought about by the energization of magnet MM. These advances of the wiper of this rotary switch are brought about by the usual pawl and ratchet mechanism employed in such switches (not shown).

The operators mechanism or set of registers by which she determines the number of impulses to be transmitted to the switches S, S and S is shown in Fig. 3. The desired circuit arrangements are established by the operator depressin manually operable sets tend to the districts, thousands, hundreds,

tens and units, by which the called-for lines are designated. These keys are designed to be mechanically locked when once depressed. Themagnets LM IUM LM Lli P and LN 5 operate upon energiza-tion to release the keys which are restored to normal position by means not shown, but which are used in apparatus of this kind. Each key, when depressed, closes a portion of a controlling circuit, which is instrumental in determining the number of impulses transmitted.

The controlling circuits associated with the different switches and other apparatus hereafter described must be brought into successive operative stages or conditions in a certain order and at definite times. To insure the proper operation of these circuits, a number of so-called sequence switches are employed. These switches are of the type shown in U. S. patent to Reynolds and Bald win, No. 1,127,808, dated February 9, 1915. Each of these sequence switches consists briefly of a. frame wherein is mounted a rotatable shaft having a series of disks of fiber or other insulating material secured thereto. On each side of each insulating disk is a disk or circular plate of conducting metal which is cut away or skeletonized so as to provide any desired arrangements of contacts. The two plates associated with each insulating disk are electrically united by securing rivets. The rotatable disks or wipers are represented in the drawing in each in stance as a long contact. A plurality of springs or brushes is provided for engagement with each pair of conducting disks, and by means of these, and bv properly cutting away and arra ing the plates on the insulating disk, an two or more brushes arranged for engagement therewith may be electrically united at any stage of rotation of the shaft. The sequence switch positions at which the various springs or brushes are in engagement with the rotatable disk are indicated by numerals placed adjacent to the several contacts respectively.

One of these sequence switches, designated SS, is. associated with the operators set 0S which is associated with the cord circuit L. In this insta nce, the wipers 20, 21, 22, 2 3, 2%, 25 and 26 are all wipers of the same sequence switch. these various wipers the last, namely 26, is open in all positions of the switch exec" pt positions one, seven and eleven, as indicated by the numerals adjacent to it. The others are closed in all positions indicated by the numerals adjacent to them. The shaft of this particular sequence switch is rotatec in response to energization of a magnet SM. This is brought about by securing a disk 27 to the shaft of the switch, and a disk 28 to the power driven shaft 29, and arranging them so that when the magnet SM is energized, the two disks will be brought into magnetic clutch engagement. The second sequence switch, designated SS, is similarly operated upon the energization of its of this sequence switch are those designated 40 to 52 inclusive. All of these wipers are in open circuit relation in the positions of the switch indicated by the numerals adjacent to them, except the last, namely 52, which is in closed circuit relation in all those positions of the switch indicated by the numerals adjacent to it.

Similar sequence switches SS, SS2 SS, SS and SS are associated with the operators keys K K K K and K respectively. In the first of these, the sequence switch m 5 net SM actuates the switch, and the wipers 60 to 65, inclusive, form part of the switch structure. The second sequence switch of this series has a magnet Si and the wipers TO to inclusive. The third switch includes the magnet SM and wipers to 86 inclusive. The fourth switch employs the magnet SM and the wipers 9G to 95 inclusr-Je. The last of the series employs the magnet SM and the wipers 100 to 105 inclusive.

Having thus briefly set forth different portions of the equipment employed in the system, I may now proceed to a description of the operation of the system and, in so doing, the various circuits and the functions of the apparatus will be further explained.

If it be assumed that a party at sub-station M desiresto converse with a party at sub-station N, and that the complete designation of the line of t ie latter is represented by the numerals 3, l, 5, 6 and 7, the party at sub-station M will remove his receiver from its hook and. thereupon close a circuit for the line relay LB;- which will light the lamp L. The operator, upon observing the lighting of lamp L, will insert plug P into jack J or" the line L. This act will close acircuit through cut off relay CO and cord relay CL. The operation of the cut-off relay will disconnect the line relay LR from the line L and thereby extinguish the line lamp L. The energization of cord relay CL will close a circuit for the sequence switch magnet SM. It may be noted here that the normal position of the sequence switch having the magnet SM' is the first position. Conseeuently, the circuit established by the energization of cord relay CL extends battery 200 through the winding of magnet SM. I

lf or convenience of reference in tracing a circuit through a sequence switch contact,

the numeral of the wiper will be used, followed by the number of the proper position in parentheses. Thus, it the circuit be through wiper 22 when the switch is in its first position, the samewill be indicated as 22 (1). l Vith this explanation of tor-- minology, the circuit' closed through sequence magnet SM may be traced as follows: from battery 200 through the winding of a magnet SM, wiper 22 (1) and front contact and armature of relay CL to ground. The resulting energization of magnet SM draws the disks 27 and 28 together and the advance of the switch begins. When the switch moves from its first position, the starting circuit through wiper 22 (1) is interrupted, but a maintaining circuit for the magnet SM is continued through wiper 26 to ground, the contact 26 having closed as soon as it passed from the first position. This circuit will be maintained until the sequence switch has reached its seventh position, when contact 26 will open its circuit and the sequence switch will be stopped in its seventh position. In this position the operators set OS will be brought into circuit through wipers 20 (7) and 21 (7 The operator will then receive the order from the calling party. The closing of contact 25 (7) establishes a starting circuit for the sequence switch magnet 8M since, as before, the contact 31 (1) of the latter switch is a normally closed contact, the first position being the normal position of the second sequence switch. The maintaining circuit through sequence switch contact 39 will be maintained only until the sequence switch reaches its second position. Thus, the second sequence switch is moved to its second position. As soon as the operator receives the order of the called party, she sets up the number, as hereinafter more fully explained, upon the keys K K K K and K As soon as this is done, she may free'her set from connection with the cord circuit L by simply throwing the listen-out key LO which will close a circuit for magnet SM through 22 (7) and key L0 to ground. The maintaining circuit for this magnet will be established. through wiper 26 until the eleventh position of the sequence switch is' reached. This movement of the sequence switch will free the operators set OS. If the operator again desires to listen in, she may establish a new starting circuit for the magnet SM by closing key L to ground, thereby establishing a circuit through 24 (11), and the maintaining circuit through contact 26 will be maintained until the sequence s'vitch again gets around to the first position. When this position is reached, the relay CL still being energized, the circuit of magnet SM will be established through. contact 22 (1) so as to move the switch out of its first position and then it will be continued through contact 26 until the seventh position is again reached and the operators set thereby brought into circuit.

Now, returning to the second sequence switch, namely, the one having magnet SM it will be seen that after the same is moved to the second position, a starting circuit for the third sequence switch will be established at contact (2), and at the same time and by the same contact, a ground connection will be established with the contact 201 of the bank of contacts on the cord finder switch S The starting circuit for the magnet SM may be traced from battery 202 through the winding of magnet 3M contact a8 (1), conductor 203 and contact 30 (2) to ground. In this instance, as before, the normal position of the third sequence switch, namely, that having the magnet Sh is the first position. The closing of sequence switch contact 3% (2) will also close a circuit for control relay CE. in the same way the closing of sequence contact (2) will place a ground upon conductor 20%.

When the third sequence switch is started by the closing of sequence contact 30 (2), the switch will be stopped at the second position by reason of the opening of sequence switch 52 (2) as before explained in connection with the other switches. The closing of sequence contact 50 (2) starts the cord finding switch S by closing a circuit through its advancing magnet All which may be traced from the live pole or battery 205, through the winding of magnet AM con tact 50 (2), normal contact 206 of test relay TH to ground. The energization of magnet .Ah" 1 by drawing upon its armature 207 forces the roller 208 against the vertical spindle 209 of the switch S and causes the latter to be moved upward by the constantly rotating disk 210. This upward movement continues so long as magnet jiM remains energized. This latter magnet, however, is deenergized as soon as test wiper 211 of switch S encounters a contact such as 201, upon which there is a ground connection. When such a ground connection is reached, the test relay is energized by the closing of a circuit which may be traced from the live pole of battery 212 through winding of test relay TH, sequence contact 47 (2), switch wiper 211, back contact 201 and sequence contact 30 (2) to ground. The closing of this circuit energizes relay TH to in terrupt the circuit All l at normal contact 206. At the same time, relay TH is held up by the closing of a. locking circuit which may be traced from the live pole of battery 212, through the winding of relay TH, quence switch contact 4? (2), closed contact 213, switch wiper 2142, switch bank contact 215 and sequence contact 30 (2) to ground. The energization of relay TH by actuating this contact 206 also closes a new starting circuit for the associated sequence switch, which may be traced from the live pole of battery 202, through the winding of magnet Ell /l sequence switch contact 48 (2), closed contact 206 to ground. The maintaining circuit for this magnet 8M is not continued by contact 52 beyond the third position of the switch. 7

At the time sequence switch SS moved to its second position, a starting circuit was established for each of the se uence magnets Sli Shi 8M SM, and M, shown in Fig. 3 in association with the keys of the operators sending mechanism. The circuit for the first of these magnets, namely SM may be traced from live pole of battery 216, through the winding of magnet SM, normal contact 217 of magnet TM and sequence contact 40 (2) to grourid. The closing of this circuit causes the sequence switch to advance and it continues to advance notwithstanding the presence of sequence contact 65, as long as contact 217 of magnet TM remains closed. The condition of contact 217 will be maintained until the sequence switch SS reaches the third position. This is true because, under the assumption that the called-for line is that represented by the numerals 3, a, 5, 6 and 7, the contacts of the key K associated with this sequence switch, which is the third key in the bank, will not be included in circuit until the sequence switch has reached its third position. When this third position is reached, a circuit is closed from the live pole of battery 218 through the winding of magnet TM sequence switch contact 63 (3) and the third key K to ground. The resulting energization of magnet TM will open the starting circuit of sequence magnet 8M and thereby prevent its moving beyond the third position, and the sequence switch contact 65, by reason of being grounded between the second and third positions, will insure a full advance of the sequence switch to the third position, no matter at what point in the passage of the switch from the second to the third position the starting circuit may be opened at contact 217. As before pointed out, the keys of this bank when depressed are held mechanically locked in depressed position until released by the associated restoring magnets LM LM etc. The movement of the sequence switch to the third position in this manner brings about a closure of sequence switch contact 62 (3), which is instrumental in the control of the rotary switch 8*, which will be hereinafter more fully pointed out.

In like manner, the closing of sequence contact 40 (2) causes the sequence switches associated with the magnets SM, SM SM and SM to move to the fourth, fifth, sixth and seventh positions, respectively, in. ac-

cordance with the depression of the fourth key K fifth key K sixth key K and seventh key K of the sending mechanism. The operation in each case is the same as that described in connection with key K and the sequence switch having the magnet SM? In this instance the contacts corresponding to the contact 217 are designated 219, 220, 221 and 222 respectively. The movement of sequence switch SS to the fourth position closes sequence contacts (4:) and 72 (4E). The moving of the next sequence switch SS to the fifth position closes sequence contacts 80 (5), 81 and 83 (5). The moving of the next sequence switch SS to the sixth position closes sequence contact 91 (6) ,7 and the movement of the last sequence switch to the seventh position will close se- (11181106: contact 102. (7 The closing of these various sequence contacts is instrumental in the control of the rotary switch S and its associated mechanism, which will be later pointed. out in detail.

Returning now to the third sequence switch SS it will be remember that the circuit by which it was moved to the third position has been traced. It remains in this position untilthemagnets TM TM T M TlV and TM are energized by the depression of the keys as before explained. As soon as the energization of these magnets has taken. place, the sequence switch magnet SM is again energized to advance the sequence switch SS from its third to its sixth position. This starting circuit for magnet 8M may be traced from live pole of battery 202, through the winding of said net,-sequence contact 48 (3), conductor 223, closed contact 224 of magnet TM closed contact 225 of magnet TM closed contact 226 of TM closed contact 227 of magnet TM and closed contact 228 of magnet TM to ground. As before, the sequence switch contact 52 insures the movement of the sequence switch to thesixth position and prevents its stopping at an intermediate point.

As soon as the sixth position of the sequence switch SS is reached, the fundamental circuit by which impulses are transmitted to the selector switch S is closed at sequence switch contact 51 (6). This fundamental circuit extends from the live pole of battery 229, through the winding of control relay CR, sequence switch contact 34 (2), conductor 230, bank contact 231 of switch S wiper 232 of said switch, normal contact 233 of relay 23 1, the windings of stepping relay ST, sequence switch contact 51 (6), wiper 235 of switch S bank contact 236, conductor 20% and sequence switch contact 35 (2) to ground. It may be noted here that contact 237 of relay CR, when closed upon the energization of said relay, together with sequence switch contact 34 (2), provides an. alternative path forv current to that relay, through sequence switch contact 34: (2) just traced. In this way the relay GR is held up by current flowing over both paths, but the latter is relied upon to hold it up when the associated sequence switch moves to the third position. The energizetion of relay CR also moves contact 238 from its normal to its alternate position. By this movement a starting circuit is established through the second switch, namely that having magnet SM to move it from its second to its third position. This circuit may be traced from the live pole of battery 239, through the winding of magnet SM sequence switch contact 31 (2) and alternate contact 238 to ground. As before explained, upon this movement of the switch from the second position to the third position, the control relay GR is held up through the path including its contact 237 and sequence switch contact 3% (3). Likewise conductor 204: is still connected to the ground through sequence switch contact 35 lilovenient of the sequence switch to its third position starts the advance of the selector switch S. This is accomplished by closing a. starting circuit which may be traced from the live pole of battery 240 through the winding oi magnet AM, sequence switch contact 37 (3) and alternate contact ofrelay CE, 2-38 to ground. The magnet AM by its euergization brings the stern 2 H of the switch into engagement with the constantly rotating disk 242 and thereby causes the switch wipers to be moved upwe. 'd over the bank contacts. In this type of switch, the wipers are moved vertically to a particular group of bank contacts, and then they are actuated. to automatically select idle contacts in that particular group. To insure a full advance from one group to the next, the switch S is provided with a commutator C, by which a circuit is maintained for control relay CR until the switch wipers have reached the first set of terminals of the desired group. This circuit extends from the live pole of battery 229 through the winding of relay CR, sequence switch contact 8-1 conductor 24 3, commutator strip 24% and brush 24:5 to ground. From this it follows that no matter what may otherwise happen to the fundamental cir cuit, the requisite advance of the wipers from one group to the next is insured. When the full step is thus obtained, the brush 245 passes on to an insulating segment of the commutator strip 24% and opens the circuit just traced. Now that the desired group is reached, the fundamental circuit ceases to maintain the relay CR energized, and the latter, by restoring its contact 238 to normal position, opens the circuit o'lt' advancing magnet A M, and the pawl 246 engages spindle 24. 1 to hold the switch in its advanced position.

he closing of normal contact 238 oi? relay CR establishes a new starting circuit for magnet SM of the sequence switch 38, which includes contact 31 (3) and normal contact 238. This circuit, together with those established by sequence switch contact 39, insures an advance of the sequence switch from the third position to the sixth position. In this position, the selector switch S is set in operation to select an idle trunk L of the group to which it has been moved. The closing of sequence switch contact 36 (6) energizes test relay TR by closing the circuit from live pole of battery 247 through the lower winding of relay TR and contact 36 (6) to ground. The energization of this latter relay at once completes a circuit from battery 2&7 through its upper winding and alternate contact 2&8, to the test wiper 249 of switch S. As long as the test wiper 249 engages contacts 250, which are grounded, the circuit through the upper winding of test relay TR will be maintained. The bank contacts 250 thus engaged, will, when associated with busy lines, receive their ground connections through multiple contacts which are engaged by other switches, and the ground connection will be supplied in such cases through wiper 249, normal contact 24:8 and sequence contact 35 (7 to 16).

The advance oi. the selector S for the purpose of picking out the idle trunk is not brought about until the associated sequence switch SS is moved to the seventh position. As soon as relay TB is energized, it closes alternate contact 251, thus closing in turn a starting circuit for magnet 8M which may be traced from the live pole of battery 239 through the winding of magnet SM sequence switch contact 38 (6) and alternate contact 251 to ground. By the closing of this circuit and the cotiperation of sequence switch contact 39, the sequence switch SS is moved to its seventh position. As a result a circuit is closed for advance magnet All. It may be traced from the live pole of battery 210, through the winding of magnet AM, sequence switch contact 37 (7) and alternate contact 251 to ground. This circuit is maintained so long as test relay TR remains energized by reason of the wipers 2&9 and grounded contacts 250. As soon as relay TB is deenergized by reason of wiper 24:9 engaging an ungrounded contact 250, corresponding to an idle trunk L the circuit for magnet AM will be interrupted at contact 251. Thus the switch S will be left in engagement with the bank contacts of an idle trunk and the circuit of the calling line will have been ext-ended through to a second selector S As soon as relay TB- is thus deenergized, the restoration oi" normal contact 251 will close a circuit for sequence switch magnet 5M through sequence switch contact 38 result will be that the sequence switch SS will advance to the eleventh position. In this position, the fundamental circuit will be extended by sequence contacts 32 (11) and 33 (11), through the wipers 252 and 253, bank contacts 254 and 255, and the strands of trunk L to the wipers 256 and 257 of a second selector switch S which will be operated by further impulses to extend the circuit of the calling line.

Before considering the operation of this .secondselector S it may be well to return again to the fundamental circuit and see how the impulses for the group selector are transmitted to the first selector 5%. When the fundamental circuit was traced, it was shown that relay CR was energized and the results of its energization have been pointed out. At the same time the stepping relay ST shown in Fig. 2, was energized. The. result of this energization is to close a circuit for the motor magnet MM of switch 8*, which may be traced through the live pole of battery 258 through the winding of magsegment of commutator segment 0, relay ST deenergizes and opens the circuit of motor magnet MM, and leaves the wiper 260 of switch S on contact 261. As the wipers 2&9, 252 and 253 of switch S move forward over one group of contacts, the brush 245 of commutator C passes over an insulating segment and opens. the short-circuiting path to ground. and thereby again allows current through ST and again close. the circuit through motor magnet Mlili. This results in advancing wiper 260 into engagement with contact 262. As the brush 24-5 continues on its upward travel, relay ST again is shunted through the commutator C, and

.circuit of magnet MM is opened, and the cannot be found until the wiper has passed. from contact 263 and engaged contact 26%. These advance steps. of the wiper 260 spond exactly with the first digit 3 of the the live pole of battery 265 through the Winding of magnet 234, sequence switch contact i3 (6), sequence switch contact 62 conductor 266, contact 264:, wiper 260, normal contact 267 to ground. The resulting energization of magnet 234: opens the fundamental circuit at contact 233 and prevents the further advance of switches. S and S Wiper 260 of switch S" is therefore'left on contact 264: and brushes 2 19, 252 and 253 are left resting on the firstset of terminals 250, 25 i and 255 of the selected group. This completes the transmission of the first set of directive impulses. The commutatorblo'ck G is provided with another commutator similar to 244: by means of which the brushes 249, 252 and 253 are accurately centered on terminals 250, 25 i and 255 but which is not described or shown on the drawings. since it and its function are well known in the art. The switch S immediately follows to pick out an idle trunk L in the manner previously described, and the sequence switch SS associated with the switch S, extends the rundamental circuit through to the second selector S in the manner previously described. In order to free the switch S for the transmission of the next set of impulses corresponding to the thousands digit in the particular number assumed, sequence switch SS is advanced from its sixth position to its seventh position. The circuit by which its magnet SM is started, extends from the live pole of battery 202 through magnet SM sequence switch contact 45 (6) and closed contact 268 of magnet 234C to ground. The resulting closure of sequence 5 *itch contacted (7) establishes a circuit for motor magnet MM, which is self-interrupting at contact 267 and consequently the wiper 260 is advanced step-by-step over the remaining contacts back to its normal posi tion. This circuit may be traced from the live pole of battery 258 through the winding of magnet MM, sequence contacts 44 (7). contact segment 269, wiper 260 and contact 267 to ground and is interrupted by wiper 260 disengaging contact segment 269 when the normal-position is reached.

As soon as the wiper 260 of switch S reaches its normal position, it establishes a new starting circuit for sequence switch magnet Fal /T which may be traced from the live pole of batter; 202 through the wind- .ing of said magnet, sequence contact 46 7}. wiper 260 and normal contact 26? to ground. As a result, the sequence switch is'moved to 270 and contact 292 or" switch S its eighth position. As sequence switch SS passes out of the sixth position, through the seventh position and into the eighth position, magnet 23% is placed on open circuit, and it contact 233 closes the fundamental circuit at this point. Likewise sequence switch contact 51 (S) closes the fundamental circuit at the remaining open point. The sequence switch also places the conductor running from magnet 23% in circuit with sequence switch contact L3 (8) and sequence switch contact (4:), conductor The oporation of sending impulses for the actuation of the second selector S is similar to that heretofore described in connection with the operation of the first selector S, but, in this instance, the switch 3 differs from the switch S in having a number of sets of brushes or wipers in accordance with the disclosure of the aforesaid patent to Reynolds, 1,l )3,623, and the particular set of brushes must first be selected in response to transmitted impulses, and then the particular group of bank contacts must be directively selected in response to second set of impulses. The next operation of the switch is to automatically pick out an idle trunk L The first set of impulses by which the desired wipers or brushes are selected is transmitted over the fundamental circuit, while the rotary switch S moves from its normal position to contact 292. When this contact is reached, the magnet 23- is again energized by reason of the closure of the circuit through wiper 260 and normal contact 267. As soon as the magnet 23% is energized by reason of the closure of the circuit through contact 292 and wiper 260, its contact 268 closes path to ground by which a starting circuit for the sequence magnet SM is established. his circuit includes the sequence switch contact to (8). its a result oi closing this circuit, sequence switch is advanced to the ninth position and the wi; er 260 of the rotary switch 3 is advanced to normal, thereby placing the apparatus in condition for the sending oi the next set of impulses by which the group of bar k contacts are selected by the wipers of the switch S its soon as wiper 260 of switch ti reaches normal, it again closes a starting circuit for uence magnet SM this time through sequence switch contact 46 (9) This at once advances the sequence switch to its tenth position, and by reason of sequence switch contact 42 (10), the winding of magnet connected in circuit with sequence switch contact 72 (4:), 81 (5), conductor 271 and contact 262 of witch 5%. Again impulses are transmitted over the fundamental circuit which advances the wipers of the switch .53 to the desired group, and at the same time, the wiper 2600f switch S is ad vanced to engagement with contact 262 as before, the wiper 260 is advanced to normal '3. readiness for the next of impulses. As magnet 234% was energized, its contact 268 closes a tarting circuit for sequence switch magnet Sit l which. extends.

through sequence switch contact 45 (10) and closed contact 268 to ground. This move ment of the sequence switch from the tenth position to the eleventh position closed quence switch contact a6 (11) so that as soon as wiper 260 of switch 3* reached its normal position, a new starting circuit was provided for magnet Slii by sequence contact 46 (11), wiper 260 and relay contact 26? to ground. As a result, sequence switch SS is again advanced another step, namely to the twelfth position. in this position, a path for current is provided through the winding of magnet 23% through sequence switch contact 42 (12), sequence switch contact 82 (5), conductor 272 to contact 261 oi the switcl'i 5*. As impulses are transmitted ver the fundamental circuit, the wiper 260 will in this case advance into engagement with contact 261, and thereupon magnet 23%: will be energized as before. The set oi: impulses which brings about this advance switch S5 is the set by which the desired brushes oi the connector switch S are selected. soon as magnet 23%. is energized, sequence switch SS is at vanced by reason of the closure of the path through sequence contact 45 (12) and closed contact 268 of magnet 234:. A ain wiper 260 of switch S advances to normal, and when its normal position is reached, the new starting circuit for magnet 5M will be closed through sequence contact -i6 (l3) and the sequence switch will be advanced to the fourteenth position. in this latter position, a connection for magnet 23a is provided through sequence switch contact ll (1d), sequence switch contact 91 (6), and conductor 273 to contact 274 of switch S. As impulses are transmitted over the frndae mental circuit to pick out the group of bank contacts, the switch S will have its wiper 260 advanced over its contacts until contact 27a: is encountered. Thereby magnet 234: will be energized with the result that the current impulses sent over the fundamental circuit will cease and sequence switch SS will be advanced by reason of the closure of sequence switch contact e5 (14) and relay contact 268. Following this, the wiper of switch S will be advanced to normal, and the sequence switch SS will be advanced to it sixteenth position. In this latter position, the magnet will, be connected in circuit with sequence switch contacts 41 (16), sequence switch contact 102 (7), conductor 27 5 to contact 2'76 of switch 8*. As before, the impulses will be transmitted over the fundamental circuit until the wiper 260 engages contact 276. The impulses thus transmitted will cause the connector switch S to pick out the particularcontacts of the called line L which is desired. As soon as contact- 276 'is encountered by wiper 260, magnet 234 will be energized to cut off the sending of impulses and to close a new starting circuit for sequence magnet SM by way of sequence contact if) (16) and contact 260 of magnet 23%. Thus, the sequence switch SS will be advanced to position 17 and as a consequence the wiper or" switch S will be brought to its normal position by reason of the closure of sequence switch contact 44 (17). As soon as wiper 260 reaches its normal position a circuit is closed for the advance of sequence switch SS This circuit extends from ground at contact 267 of motor magnet Mil /i through said contact, wiper 260, sequence switch contact 4.6 (17), conductor 277, sequence switch contact 38 (11) and the winding of magnet SM to battery 239. As a result of the closing of this circuit, sequence switch SS advances from position 11 to position 16. As soon as it passes out oi -position 11, sequence switch contacts 32 (12 to 16) and 33 (12 to 16) complete the strands of the cord circuit L to the wipers of the switch S and interrupt the connection of the fundamental circuit to the latter. lhe movement of sequence switch SS from position 11 opens the ground con nection at sequence switch contact 30 (11) by which the testing and holding magnet TH was held up, and consequently the latter is de'e'nergized and a starting circuit is established for sequence switch SS by way of sequence switch contact 48 (17) and back contact 206 of relay TH. Consequently, sequence switch SS advances from position 17 to position 18. As soon as this position is reached, a circuit is closed for return mag net El /l of cord finder switch S This circuit extends from battery 205, the winding of magnet. hM and sequence switch contact as (18) to ground. As a result, the retain: ing pawl of the switch is withdrawn, and the associated power driven disk 278 draws the switch wipers out of engagement with the associated bank contacts. As soon as this switch reaches its lowermost position, it closes contact 279 to ground, and thereby establishes a new starting circuit for sequence switch SS by which it is moved from position 18 to position 1, the latter being its normal position. This starting circuit includes sequence switch contact 280 (18) and closed contact 279.

It maybe pointed out here that when the sequence switch SS was moved from its third to its fourth position, and while it was in both its fourth and fifth positions, a

circuit was closed for each of the restoring magnets LM LM LM LM, LM throughsequence switch contact 40 (45) to ground. The operation of these magnets re leased the mechanically held keys K 1 K K K respectively. The sequence switches associated with these keys are not restored to any particular normal position, but may be left in any position in which they may happen to be after any given operation, and then when a subsequent operation is begun and the starting circuits of those switches are established, theywill continue advancing from position to position until they come into that one which is determined by the particular key depressed in a manner heretofore explained.

Thus the cord finding selector S the ro tary switch S and the key mechanism 01": Fig. 3 are all freed from the circuit between substations M and N, and are ready for use in connection with other similar circuits.

When connection has been established with the called line, ringing current may be applied thereto in any suitable way, and in case the line is busy, suitable indicating devices may be employed to apprise the operator of that condition. A talking battery 281 and suitable repeating coil windings 282 and 283 may be employed in the cord circuit, or a circuit of different design may be utilized if desired. In association with this cord circuit, supervisory signals indicated by the magnets 284 and 285 are also to be incorporated, so that the operator may have supervision of the connected lines.

When the supervisory signals indicate that the subscribers have completed their conversation, theioperator will withdraw the plug P from the jack J, and thereupon deen'ergizes the cut-off relay and cord relay L, by the former restoring the line circuit to its normal condition, and by the latter closing a starting circuit for sequence switch magnet SM? of sequenceswitch SS which may be traced from the winding of said magnet through sequence switch contact 31 (16), sequence switch contact 23 (1), and back contact 286 of relay CL. The closing of this circuit will cause sequence switch SS to advance from its sixteenth position to its eighteenth position. In its eighteenth position, there will be a return'circuit-closed for return magnet RM, which may be traced from battery 240, through the winding of magnet RM and sequence contact 36 (18) to may be traced from the winding'of magnet SM through sequence switch contact 38 (18) conductor 288, commutator contact 289 and brush 290 to ground. By the closing oi. this circuit, sequence switch will be ad vanced from its eighteenth to its first or normal position. The remainder of the switches, namely, selector S and connector 5 will be released by suitable releasing circuits associated with them and'controlled by the restoration of switch but as these constitute no part oi the present invention, they need not be described. Thus, all the parts of the apparatus are brought back to normal position in readiness for subsequent operations.

\Vhat is claimed is:

1. In combination, two selectively operable switching devices each having a plurality of positions, a controlling device for predetermining the position to which the lirst of said devices should move, a variably operable switch for arresting the movement of said controlling device, means controlled by the second of said devices for moving said first device toward said predetermined position, and means controlled by the first device for stopping the second device when said first device reaches the predetermined position.

2. In combination, two switching devices each having a normal and a plurality of operating positions, a controlling device for iredetermining the operating position to which the first of said devices should move, a variably operable switch for arresting the movement of said controlling device, means for moving the second of said devices, means responsive to the movement of said second device for moving the first device from normal toward said predetermined position, and means operative upon the movement of said first device into said predetermined position for arresting the movement of said second device.

3. In a telephone exchange system, a plurality of lines, means including a selector switch for establishing a connection between a calling and a called line, a controlling device for said selector switch, said selector switch and said device having a normal position and a plurality of operating positions, at second controlling device for predetermining a position to which said first controlling device should move, a variably operable switch for setting said second controlling device, means responsive to the movement of said selector switch through operating positions for moving said first controlling device from normal toward said predetermined position, and means operative when said first device reaches the predetermined position for arresting the movement of said selector switch.

4. In a telephone exchange system, a plurality of lines, means including a selector switch for establishing a connection between a calling and a. called line, a controlling device for said selector switch, said s itch and said device having a normal position and a plurality of operating positions, a variably operable register for predetermining a position to which said controlling device should move, a variably operable switch for controlling the setting of said register, means responsive to the movement of said selector through operating positions for moving said controlling device from normal toward said predetermined position, means operative when said device reaches the predetermined position for arresting the movement of said selector, and means for moving said controlling d vice from said operating position to its normal position.

5. In combination, two selectively operable switching devices having a normal position and a plurality of operating positions, an operating magnet for each of said devices, a variably operable, electrically controlled register switch for predetermining a position to which the first oi said devices should move, means for operating said register switch, means controlled by the other device during its ope "ation for causing the magnet oi' the first device to operate, means actuated upon the movement of said first device to the predetermined position for arresting the movement of said second device, means controlled by said first device for operating its magnet until it is moved from the predetermined to the normal position, and means for preventing during this last mentioned movement of the first device the operation of the second device.

6. In combination, two selectively operable switching devices having a normal position and a plurality of operating positions, an operating magnet for each of said devices, means including an electrically controlled register switch for predetermining an operating position to which the first of said devices should be moved, means for operating saidregister switch, means responsive to the operation of the second of said devices for causing the operating mag net of the first device to move it in one direction from its normal to the predetermined position, means operative upon the setting of said first device to the predetermined position for arresting the movement of the second device, and means operative thereupon and controlled by the first device for causing its operating magnet to move it in th same direction, from the predetermined to the normal position.

7. In combination, two selectively operable switching devices having a normal position and a plurality of operating positions, an actuating magnet for each of said devices, means for establishing a controlling circuit between said devices, means for predetermining an operating position for the first of said devices, means for operating the magnet of the first device by shunting the controlling circuit at the second of said devices, means for closing the circuit of the actuating magnet of the second device upon the establishment of said controlling circuit and for maintaining it closed during the shunting of the controlling circuit, means operative upon the setting of the first device to the predetermined position for opening said controlling circuit, means operative thereupon for opening the circuit of the magnet of the second device, a self-interrupted circuit for the magnet of said first device, closed while said first device is moving from the predetermined to the normal position.

8. In, a telephone system, telephone lines,

link circuits for uniting said lines into conversational circuits, an electrically controlled switch for use in establishing such and connections whereby said register mechanism provides circuits for operating said interrupting means whenever said step-bystep switch reaches predetermined positions corresponding to the particular setting of said register mechanism.

9; In a telephone system, telephone lines, link circuits for uniting said lines into conversational circuits, a link circuit finder switch, an automatic switch for use in connecting said link circuits, a step-by-step switch for use in determining the extent of movement of said automatic switch, an electrically controlled sequence switch associated with said finder and step-by-step switches for controlling their operations, and means whereby said finder and step-bystep switches provide circuits for advancing said sequence switch.

10. In a telephone system, telephone lines, link circuits for uniting said lines into conversational circuits, automatic switches for use in establishing such conversational circuits, connections for providing a fundamental control circuit for use in advancing said switches, a relay for making and breaking said fundamental circuit, operators register mechanism for severally connecting selected paths in circuit with said relay, a switch having a series of fixed contacts in which said paths respectively terminate, means for operating said switch in response to impulses from said automatic switches, and connections with the movable contact of said switch for completing the circuit of said relay when said movable contact engages the proper fixed contact.

In witness whereof I hereunto subscribe my name this 22nd day of July, A. D

ALBEN E. LUNDELL. 

